According to the present invention, a shaft cover is attached to the front end portion of a ribbon guide shaft projecting in a cantilevered state from a side face of a printer body; cores of an ink ribbon are fitted respectively on a ribbon feed shaft and a ribbon take-up shaft both projecting in a cantilevered state from the said side face of the printer body; the ink ribbon is passed round the outer periphery of the shaft cover; then the cores and the shaft cover are pushed in simultaneously to set the ink ribbon in a predetermined certain position.